This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the presently described embodiments. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the described embodiments. Accordingly, it should be understood that these statements are to be read in this light and not as admissions of prior art.
In the oil and gas industry, a well may be drilled and a completion system may be installed at a surface end of the well in order to extract oil, natural gas, and/or other subterranean resources from the earth. Such a completion system may be located onshore or subsea depending on the location of the desired resource and/or well. A completion system generally includes a wellhead assembly through which a resource is extracted or fluids are injected. Subsea wellhead system equipment typically features cylindrical bodies which contact and rest in larger cylindrical bodies via expanding split rings, split lock rings, split load rings, or C-rings. For example, a casing hanger may use this technology to hang a casing string inside a receptacle welded to a larger casing string.
A typical subsea wellhead assembly includes a wellhead housing that supports one or more casing hangers. A casing hanger may land on and be supported by a load shoulder, which may be installed on a special running tool or may be run with the casing hanger. One type of wellhead housing has a conical load shoulder machined within its bore. In this type, the diameter of the housing below the bore is less than the diameter of the housing above the bore by a dimension equal to a radial width of the load shoulder. In another type, the wellhead housing has a groove with substantially the same diameter above and below the groove, and the load shoulder is a split ring that is installed subsequently in the groove, which allows a larger diameter bore to be employed during drilling operations. In another type, as described in U.S. Pat. No. 7,380,607, the wellhead housing has a bore containing a conical upward facing load shoulder that inclines relative to an axis of the bore; a casing hanger landed in the housing has a conical downward facing load shoulder that inclines at a lesser angle relative to an axis of the bore; and the casing hanger carries a split lock ring that is capable of supporting the hanger on the upward facing load shoulder, has an inner profile that slidingly engages the hanger's downward facing load shoulder and an outer profile that slidingly engages the housing's upward facing load shoulder, and moves between a retracted position (outer profile spaced radially inward from the upward facing load shoulder) and an expanded position (outer profile in engagement with the upward facing load shoulder).
However, in all of the above examples, the extent of split lock ring expansion, and thus the contact area and load capacity, typically is limited by the inner and outer diameters of the mating cylinders, such that one must be able to pass through the other.